The only really effective way to slim down a system Operational is by removing features that are not too popular, but with this you run the risk of being able to remove some that really interests more than one user, this being the case of the web server that had Lion integrated.
Mac OS X's default web server was not a big deal considering that there are better and free alternatives like MAMP, but for those who were looking for something simple it was perfect, and for that reason we are going to see how it can be recovered for Mountain Lion.
Thanks to a preferences panel created by Tyler Hall you can have back the option to manage web server locally, and although in my case I have MAMP -you see it in the capture-, it is not necessary to have it for Apache to work perfectly.
Download | Web Sharing preference pane
Source | OSXHints
To say that the Mac OS X default server has been removed and that it was "no big deal" when compared to MAMP is simply not knowing what you are talking about. MAMP is nothing more than a bundle of the same Apache server together with the MySQL server and PHP; Any developer with a minimum of knowledge will be able to configure the "native" Apache for Mac OS X 10.8, which is still present, along with the PHP interpreter (which also incorporates Mac OS X), as well as download and install MySQL database service (even PHPMyAdmin or any of the different clients that exist to manage / administer MySQL) without using MAMP.
Having lost the ability to manage Apache startup from the control panel is no drama, given its limited options since it only served to enable or disable the service and the user folder that Apache accesses, all this can be configured in the appropriate files. To do it all using an installer and clicking "Next" Windows already exists.